Why Ingress manages external access in Kubernetes - Visual Breakdown

Process Flow - Why Ingress manages external access

User sends request to cluster IP

↓

Ingress Controller receives request

↓

Ingress rules check request path & host

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Route to Service A

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Service A Pod

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Response sent back

Ingress acts as a gatekeeper that receives external requests and routes them inside the cluster based on rules.

Execution Sample

Kubernetes

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: example-ingress
spec:
  rules:
  - host: example.com
    http:
      paths:
      - path: /app1
        pathType: Prefix
        backend:
          service:
            name: app1-service
            port:
              number: 80

This Ingress resource routes requests with host 'example.com' and path starting with '/app1' to the 'app1-service'.

Process Table

Step	Request Host	Request Path	Ingress Rule Match	Service Routed To	Action
1	example.com	/app1/home	Host matches example.com, Path prefix /app1	app1-service	Route request to app1-service
2	example.com	/app2/home	Host matches example.com, Path prefix /app1 (No)	No match	Return 404 or default backend
3	other.com	/app1/home	Host does not match example.com	No match	Return 404 or default backend

💡 Requests stop routing when no matching Ingress rule is found or after routing to the correct service.

Status Tracker

Variable	Start	After Step 1	After Step 2	After Step 3
Request Host	none	example.com	example.com	other.com
Request Path	none	/app1/home	/app2/home	/app1/home
Matched Service	none	app1-service	none	none

Key Moments - 2 Insights

Why does a request with host 'other.com' not get routed to any service?

Because the Ingress rule only matches requests with host 'example.com' as shown in execution_table row 3, so no routing occurs.

What happens if the request path does not start with the specified prefix in the Ingress rule?

The request does not match the path rule and is not routed to the service, as seen in execution_table row 2 where '/app2/home' does not match '/app1' prefix.

Visual Quiz - 3 Questions

Look at the execution table, which service does the request with path '/app1/home' and host 'example.com' route to?

A app1-service

B app2-service

C No service, returns 404

D Default backend

💡 Hint

Check row 1 in the execution_table where host and path match the Ingress rule.

At which step does the request fail to match any Ingress rule due to host mismatch?

A Step 1

B Step 2

C Step 3

D None

💡 Hint

Look at the 'Request Host' column in execution_table row 3.

If the path prefix in the Ingress rule changed to '/app2', what would happen to the request at step 1?

A It would route to app1-service

B It would not match and return 404

C It would route to app2-service

D It would route to default backend

💡 Hint

Compare the path '/app1/home' with the new prefix '/app2' in execution_table logic.

Concept Snapshot

Ingress manages external access by acting as a traffic router.
It listens for requests from outside the cluster.
Routes requests based on host and path rules.
Sends traffic to the correct internal service.
If no rule matches, returns 404 or default backend.
Ingress simplifies exposing multiple services securely.

Full Transcript

Ingress in Kubernetes manages external access by receiving requests from outside the cluster and routing them to internal services based on rules. The Ingress controller checks the host and path of each request against defined rules. If a request matches a rule, it is forwarded to the specified service. If no rules match, the request is rejected or sent to a default backend. This allows multiple services to be exposed through a single external IP with clear routing rules.